WASHINGTON — Federal agencies have cut their travel expenses by $3 billion dollars over the past three years in the aftermath of a series of high-profile conference excesses, a government official said Tuesday, but senators questioned whether the cuts can be sustained.

Beth Cobert, an official at the White House Office of Management and Budget, told the Homeland Security and Governmental Affairs Committee that agencies are now having “the right conversations” about spending on travel and conferences. She attributed the cuts to increased transparency, oversight and use of technologies like videoconferencing.

Although senators said spending in the past had been “excessive” and “unnecessary,” they questioned the sustainability and potential harm of the decreased spending.

“While it is important that agencies make efforts to eliminate any wasteful spending on conferences and travel, we must be careful that we don’t unduly restrict the ability of our agencies to interact with outside groups,” said Tom Carper, D-Del., the chairman of the committee.

The agencies were required to reduce travel costs from fiscal year 2010 spending levels by 30% after a highly criticized General Services Administration conference in 2010. At the $800,000 Las Vegas conference, clowns and mind readers entertained agency officials on the taxpayer’s dime.

The public response to the GSA conference set off a domino effect of investigations into similar high-cost conferences, such as a 2011 Internal Revenue Service conference in California and two Department for Veterans Affairs conferences in Orlando.

At the IRS conference in Anaheim, Calif., which cost $4.1 million, managers were greeted with engraved pens and briefcases. In the same year, the Department of Veterans Affairs spent $6.1 million on two Florida conferences, where employees improperly accepted gifts that included helicopter rides.

Carper asked if any rules were on the books to limit conference spending in resort locations. The government spent just $92,736 on Las Vegas hotel rooms in fiscal year 2013 compared with $2.5 million in 2010, according to a USA TODAY analysis of federal spending data. Cobert said no such guidance existed, and locations are chosen based on cost and the conference’s audience.

STORY: Federal agencies shunning Las Vegas for travel

Oklahoma Sen. Tom Coburn, the top Republican on the panel, said it’s important for Congress to take action that “would have prevented every single one” of the highly publicized examples of wasteful spending on government conferences.

“History, it is my fear, will repeat itself,” Coburn said. “That’s why it’s so important for Congress to take action.”

In July, Coburn introduced a bill aimed at limiting government conference spending by converting into law many of the same measures now used by the OMB. Congress is also moving this week on a spending bill for the rest of this year that will restrict government agency spending on conferences.

But Sen. Jon Tester, D-Mont., emphasized the importance of travel for federal agency employees so they can reach out to citizens, and he called on the OMB to separate travel spending from conference spending.

“We’ve got to be careful,” he said. “We’re looking at top-line numbers here.”